Hydrothermal Conversion of Alginate into Uronic Acids over a Sulfonated Glucose‐Derived Carbon Catalyst

Abstract Alginate, the major constituent of algal biomass, was hydrolyzed into uronic acids over sulfonated glucose‐derived carbon catalysts using water as a green solvent under mild temperature conditions (100, 120, and 140 °C). The catalytic activity was compared with that of sulfuric acid and other commercial solid acid catalysts such as carbon black, activated carbon, Amberlyst‐15, and zeolites. The carbon catalysts were further treated with nitric acid or sulfuric acid to impart acid properties. The sulfonic group is an active site in the catalysis of the hydrolysis of alginate, and phenolic hydroxyl and carboxylic groups on the carbon surface showed negligible effects on the hydrolysis reactions in the temperature region. A high local acid density of the sulfonated glucose‐derived carbon catalyst (Glu‐SO3H) facilitates the cleavage of the 1,4‐glycosidic bond as alginate adsorbs ont…